This P01 aims to develop and apply state-of-the-art methods to analyze existing but under-utilized drug abuse databases in collaboration with their owners. We address contemporary, theoretical, and applied issues in drug abuse research to understand intersections between substance abuse and AIDS risk behaviors as well as minority and gender-based health disparities. We work together with dozens of investigators from education, epidemiology, medicine, psychiatry, psychology, public health, social work, and sociology who own exciting substance abuse data to develop models that test current theories, especially on epidemiology, prevention, intervention, and treatment of drug abuse, using modern multivariate psychometric and statistical methods to control for measurement errors, biases, and other confounds. The Models and Methods Project develops analytic techniques (e.g., improved structural equation methods for small samples, missing and nonnormal data, outliers, dependent and hierarchical data, functional imaging) that hold special promise for improving the quality of drug abuse and AIDS research. The At-Risk Project studies substance abuse related data sets on vulnerable populations (substance abusers, homeless people, individuals who are HIV positive or who have AIDS, victims of domestic abuse, runaways, gang members, and others at high risk for AIDS or drug abuse) with methods to control the sampling, measurement, distributional and other biases that may exist. The Community Project studies drug abuse etiology, adult consequences, HIV risk, intergenerational processes, general deviance, and related issues in large community-based samples, and develops and tests explanatory theories using models that permit separation of common from specific effects, control for artifacts, etc. The Latino Project uses datasets from varied Latino groups to study within- and between-Latino population drug abuse etiology, test and extend an ecological theory of Latino drug use, and study HIV risk and acculturative phenomena related to drug use. The Core Project oversees and integrates all components, hosts visiting scholars, provides computer facilities, and sponsors a mentoring program for disadvantaged students.